Added attributes inheritance support

[mingazhev]

Context

Allows to use inheritance to get Allure labels and other report information Closes: https://github.com/allure-framework/allure-csharp/issues/384

Checklist

• [x] Sign Allure CLA
• [ ] Provide unit tests

CAUTION

These changes may break backward compatibility in cases when existing behaviour is expected: base class attributes are not ignored now

[CLAassistant]

Thank you for your submission! We really appreciate it. Like many open source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution.

---

vmingazhev seems not to be a GitHub user. You need a GitHub account to be able to sign the CLA. If you have already a GitHub account, please add the email address used for this commit to your account.
_{You have signed the CLA already but the status is still pending? Let us recheck it.}